1. Field of the Invention
This invention relates to an improved pipe joint for connecting, for example, a metal pipe and a synthetic resin tube which are used to form a pipeline having a relatively small diameter not exceeding about 15 mm for supplying oil or air to an automobile, machine or apparatus.
2. Description of the Prior Art
A known pipe joint of the type to which this invention pertains is shown by way of example in FIG. 3. It comprises a main body 21 having an axial bore 22 in which a pipe P.sub.1 is received at one end thereof. The main body 21 is provided at one end thereof with an axially projecting connecting portion 23. The bore 22 has a diameter which increases in a plurality of steps as it becomes remoter from the connecting portion 23. The connecting portion 23 has an axial bore connected with the bore 22. The main body 21 has a wall portion 24 within which the bore 22 has its maximum diameter, and which is provided therethrough with a plurality of holes 26. Each hole 26 defines a radially outwardly projecting flange 25 at the other end of the main body 21 remote from the connecting portion 23. A pair of seal rings are provided between the pipe P.sub.1 and the inner surface of that portion of the main body 21 in which the bore 22 has its minimum diameter. The pipe P.sub.1 has a radially outwardly projecting wall portion P.sub.1 ' which is located in the main body 21 when it is connected thereinto. The joint also includes a generally cylindrical supporting member 27 which can be resiliently fitted into the main body 21 through the opening at the other end thereof. The supporting member 27 has a plurality of elastic wall portions 28 each having a radially outwardly projecting shoulder received in one of the holes 26 and held against the flange 25. Each wall portion 28 has a radially and axially inwardly directed pawl engaging the radially outwardly projecting wall portion P.sub.1 ' of the pipe P.sub.1 to hold the pipe P.sub.1 in position.
The supporting member 27, however, has an open end 29 surrounding the pipe P.sub.1. The open end 29 and the holes 26 of the main body 21 allow dust, water and other foreign matter to enter the joint. The dust, water, etc. are likely to disable the maintenance of a tight seal between the seal rings and the pipe P.sub.1. When the pipe which has been disconnected is connected again, it is often difficult to obtain a leakproof connection.